1. Technical Field
The present invention relates to an image projecting apparatus, image projecting method, and medium.
2. Background Art
Conventionally, an image projecting apparatus such as a projector is widely used for projecting images and moving images that include necessary information (hereinafter referred to as “video”) on a projection surface such as a wall or a screen to present information to attendees at meetings, lectures, and presentations. The image projecting apparatus displays video by projecting it as light on the projection surface, and a presenter and audience (hereinafter referred to as “users”) see the video by recognizing light that the projection surface reflects visually. The image projecting apparatus is not only mounted on a floor or a desktop (hereinafter referred to as “floor-mounted”) but can also be suspended a ceiling (hereinafter referred to as “ceiling-mounted”). It should be noted that, in case of being ceiling-mounted, the image projecting apparatus is installed so that the bottom surface (the supported surface in case of being floor-mounted) of the image projecting apparatus faces the ceiling.
In using the image projecting apparatus, it is necessary to project the video while adjusting the amount of projection light and the brightness and intensity of the video signal appropriately. However, the use environment since environment where the image projecting apparatus is not always constant, and the illumination and intensity vary with the use environment. For example, in a use environment where illumination is high, the contrast of the projected video deteriorates, thereby reducing visibility for users. Also, in a use environment where high wavelength range light is stronger than other wavelength range light, high wavelength range reflected light of projected video decays whereas light of other wavelength ranges appears enhanced, thereby reduced visibility for users.
Thus, on the opposite surface of the supported surface of the image projecting apparatus, an illumination sensor that measures illumination of light illuminated on the opposite surface of the supported surface is usually provided. In addition, the image projecting apparatus is equipped with a function that automatically adjusts the amount of projection light and the brightness and intensity of the video signal based on the illumination measured by the illumination sensor. Consequently, brightness and color of video projected on the screen can be adjusted appropriately, thereby improving visibility for users.
In case the image projecting apparatus is mounted on the floor or the desktop (floor-mounted), the illumination sensor mainly measures illumination by light from lighting in the use environment and window (hereinafter referred to as “environment light”) illuminated on the illumination sensor directly. Meanwhile, in case the image projecting apparatus is suspended from the ceiling (ceiling-mounted), the illumination sensor mainly measures illumination by light that the floor and the desktop (hereinafter referred to as “reflecting surface”) reflect the environment light.
Consequently, in case reflectance of the reflecting surface is less than 1, illumination measured by the illumination sensor in case of being floor-mounted is different from illumination measured by the illumination sensor in case of being ceiling-mounted even in the same use environment. Thus, visibility for users differs due to the difference in installation of the image projecting apparatus even in the same use environment.
To cope with this issue, in order to convert brightness and color components of the video signal input from an external device such as a personal computer (PC), an image projecting apparatus that divides illumination range by predefined width for each case of being floor-mounted and being ceiling-mounted, sets modes corresponding to each range, and converts the brightness and color components in accordance with mode that corresponds to the measured illumination has been proposed (e.g., JP-2006-267144-A.)
In the technology described in JP-2006-267144-A, since different modes are set for case of floor-mounted and ceiling-mounted, brightness and color components are converted in accordance with different mounting statuses, thereby improving visibility for users.
As described above, in case of being ceiling-mounted, since the illumination sensor measures illumination by light that reflecting surfaces such as the floor reflects the environment light, the illumination varies depending on reflecting characteristics due to material and color of the reflecting surface. For example, reflectance of carpet is lower than flooring as for material, and reflectance of darker color is lower than whiter color. Therefore, it is difficult to measure or estimate illumination precisely and to improve visibility for users instead of considering reflecting characteristics due to material and color of the reflecting surface.
However, in the technology described in JP-2006-267144-A, standardized distinction that illumination measured in case of being ceiling-mounted approximately becomes a tenth of illumination measured in case of being floor-mounted, and reflecting characteristic of reflecting surface is not considered. Therefore, in the technology described in JP-2006-267144-A, mode can be determined by illumination widely different from actual illumination depending on reflecting characteristics of reflecting surfaces, thereby reduced visibility for users.